CHM-11 Tube

[Alan Sailer]

So I have a loaner CHM-11 boron neutron tube which is apparently the bomb when it comes to detecting neutrons. It came to me untested.

I am using a bias tee with 10Mohm in series and a 470pF capacitor to couple the output to the scope. I am using this to check out the tube.
The bias is 1500 volts on input to the network and goes down to about 700 volts on the tube. The tube is drawing about 3X the spec on the
data sheet ie 75uA vs 24uA.

Good start, nyet?

And the scope is showing jack shit. Nothing. Nada. At 50mV per division.

If anyone has any information about the expected pulse height, width and bias current on a CHM-11 tube, please let me know. The
current seller of such tubes on Ebay tells me "All this tubes snm-11 was tested in radiation laboratory on my work" so I must be the problem.

Cheers.

[Mark Rowley]

If you want to send me the tube I can test it’s operability.

Mark Rowley

[Alan Sailer]

mark,

I may do that. I want to spend a little more time playing with the darn thing.

The only project I have ever worked on that that more I try the less happens.

Sheesh...

Cheers.